this is a rather generic question with a broad range of solutions
I assume you are speaking of LP tanks? because if it was a gasoline/diesel powered truck the tanks are built into the frames and the size varies on the model of the truck and frame size.

But going on the assumption you mean LP tanks
there are 3 different sizes that are used
20lb tank which is too small for any practical use in production
33.5lb tank which is the standard used in most lifts across the board in the small class trucks
then the 43.5lb tank which is used in larger trucks

they come in steel or aluminum as standard fill or quick fill, depending on what application you wish, most tanks i see are generally quick fill tanks.

aluminum being more popular these days because of it being lighter.

if you could be more specific on what model truck this is going on and the type of fuel that might be helpful.

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